The invention relates to a method for the inductive heating of a refractory mold part or guide member by means of an inductor device. The invention also relates to the corresponding mold part or guide member.
U.S. Pat. No. 3,435,992 discloses a pouring shell for the continuous pouring of liquid metal, in particular steel. The pouring shell is inductively heated before being brought into contact with the liquid metal. The pouring shell described in U.S. Pat. No. 3,435,992 has an electrically conductive insert which is provided in the pouring shell. In addition, the pouring shell is formed of an essentially electrically nonconductive refractory material. Through an induction coil, which encompasses the pouring shell and is essentially disposed coaxially with it, the electrically conductive insert, made of preferably a graphite part, can be heated by a current having a frequency of 3 to 50 kHz. However, only the electrically conductive insert absorbs induction energy and is inductively heated. In contrast, the pouring shell is heated through thermal conduction.
U.S. Pat. No. 4,940,870 teaches of providing an entirely or partially continuous slot within a shell made of an electrically conductive material and encompassed partially by an induction device. The slot, in turn, suppresses the heating of the shell.
FR 2,609,914 discloses a pouring shell with an outer portion that can be heated inductively. Several tubes are set into the outer portion forming the pouring opening. The heat generated by the induction energy is transferred through thermal conduction to the tubes forming the pouring opening.
The disadvantage of the prior art devices described above is that the induction heat is not transferred directly but rather only through thermal conduction to the entire guide member. This is particularly the case when the guide member is not encompassed completely by the inductor device but more or less "projects" from the inductor device.
This is often unavoidable since no other solution is possible for spatial reasons. In such cases the guide member is heated extremely nonuniformly, which can lead to stress fractures and other problems.